you might just have a little kidney stone or something. I used to get them all the time, and usually I could get through it by drinking massive amounts of fluid and gritting my teeth through the worst of it. The only problem with those is that you can't always pass them, and then you need medical intervention. Or there's an underlying issue that's creating the stones, and tweaking your diet or taking some meds makes them not happen again. That's why they analyze the stones.
Mine always seemed to be brought on by having to walk in downtown Chicago. I have no idea why, but it seemed like I had one every time I got back from Chicago. Did great until I had one in 2001 that I couldn't pass. I didn't register any pain but I couldn't stop puking, and apparently I was in shock. Had to have surgery for that one
I'm glad you're going to the Dr. Your doctor will get it sorted out.